package 开始的剑指offer8月.搜索与回溯算法;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
// https://leetcode-cn.com/problems/cong-shang-dao-xia-da-yin-er-cha-shu-ii-lcof/
public class 剑指Offer32II从上到下打印二叉树II0818 {


     public class TreeNode {
         int val;
         TreeNode left;
         TreeNode right;
         TreeNode(int x) { val = x; }
     }

    class Solution {
        public List<List<Integer>> levelOrder(TreeNode root) {
            Queue<TreeNode> queue = new LinkedList<>();
            List<List<Integer>> res = new ArrayList<>();
            if(root != null) queue.add(root);
            while(!queue.isEmpty()) {
                List<Integer> tmp = new ArrayList<>();
                for(int i = queue.size(); i > 0; i--) {
                    TreeNode node = queue.poll();
                    tmp.add(node.val);
                    if(node.left != null) queue.add(node.left);
                    if(node.right != null) queue.add(node.right);
                }
                res.add(tmp);
            }
            return res;
        }
    }

}
